The importance of etching aluminum and its alloys has increased significantly within the last several years. As the electronics industry has moved into production of very large scale integrated circuits (VLSI), the need for methodology which meets the requirements for VLSI production has become increasingly acute.
The high-density, i.e. fine-line, geometries necessary for VLSI circuits make it essential that etching is anisotropic to achieve faithful delineation of patterns. It is likewise important that the etch be as uniform as possible over the entire surface of a substrate. Merely carrying out the etch for a time sufficient for all of the substrate to be etched is not the solution to uniformity, however, since this would result in overetching in the peripheral regions of the substrate. Those of ordinary skill in the art are aware of the fact that, in the etching of aluminum for VLSI production, overetching is as disadvantageous as underetching. A method of significantly improving the uniformity of etch across a substrate is provided in accordance with this invention.